use codespan_reporting::diagnostic::Diagnostic;
use codespan_reporting::diagnostic::Label;
use codespan_reporting::diagnostic::LabelStyle;
use codespan_reporting::files::Error as CodespanError;
use codespan_reporting::files::SimpleFiles;
use codespan_reporting::term::emit;
use codespan_reporting::term::Chars;
use codespan_reporting::term::Config;
use codespan_reporting::term::DisplayStyle as CodespanDisplayStyle;
use codespan_reporting::term::Styles;
use rustc_hash::FxHashMap;
use termcolor::BufferWriter;
use termcolor::Color;
use termcolor::ColorChoice as TermColorChoice;
use termcolor::StandardStream;
use termcolor::WriteColor;

use ara_source::SourceMap;

use crate::annotation::AnnotationType;
use crate::error::Error;
use crate::issue::IssueSeverity;
use crate::Report;
use crate::Reportable;

#[derive(Debug, PartialEq, Eq, Clone)]
pub enum CharSet {
    Ascii,
    Unicode,
}

#[derive(Debug, PartialEq, Eq, Clone)]
pub enum ColorChoice {
    Always,
    Auto,
    Never,
}

#[derive(Debug, PartialEq, Eq, Clone)]
pub enum DisplayStyle {
    Default,
    Comfortable,
    Compact,
}

#[derive(Debug, Clone)]
pub struct ReportBuilder<'a> {
    pub source_map: &'a SourceMap,
    pub colors: ColorChoice,
    pub charset: CharSet,
    pub style: DisplayStyle,
}

/// A report builder.
///
/// A report builder is used to build a report.
///
/// Example:
///
/// ```rust
/// use ara_source::source::Source;
/// use ara_source::source::SourceKind;
/// use ara_source::SourceMap;
///
/// use ara_reporting::builder::ReportBuilder;
/// use ara_reporting::Report;
///
/// let report = Report::new();
/// let source = SourceMap::new(vec![
///     Source::inline(SourceKind::Script, "function main(): void {}"),
/// ]);
///
/// let builder = ReportBuilder::new(&source);
/// assert_eq!(builder.source_map.sources[0].content, "function main(): void {}");
/// ```
impl ReportBuilder<'_> {
    /// Create a new report builder.
    pub fn new(source_map: &SourceMap) -> ReportBuilder {
        ReportBuilder {
            source_map,
            colors: ColorChoice::Auto,
            charset: CharSet::Ascii,
            style: DisplayStyle::Default,
        }
    }

    /// Set the color choice.
    ///
    /// Example:
    ///
    /// ```rust
    /// # use ara_source::source::Source;
    /// # use ara_source::source::SourceKind;
    /// # use ara_source::SourceMap;
    /// # use ara_reporting::builder::ReportBuilder;
    /// # use ara_reporting::builder::ColorChoice;
    /// # use ara_reporting::Report;
    /// # let report = Report::new();
    /// # let source = SourceMap::new(vec![
    /// #     Source::inline(SourceKind::Script, "function main(): void {}"),
    /// # ]);
    /// # let builder = ReportBuilder::new(&source);
    ///
    /// let builder = builder.with_colors(ColorChoice::Never);
    /// assert_eq!(builder.colors, ColorChoice::Never);
    ///
    /// let builder = builder.with_colors(ColorChoice::Always);
    /// assert_eq!(builder.colors, ColorChoice::Always);
    ///
    /// let builder = builder.with_colors(ColorChoice::Auto);
    /// assert_eq!(builder.colors, ColorChoice::Auto);
    /// ```
    #[must_use]
    pub fn with_colors(mut self, colors: ColorChoice) -> Self {
        self.colors = colors;

        self
    }

    /// Set the character set.
    ///
    /// Example:
    ///
    /// ```rust
    /// # use ara_source::source::Source;
    /// # use ara_source::source::SourceKind;
    /// # use ara_source::SourceMap;
    /// # use ara_reporting::builder::ReportBuilder;
    /// # use ara_reporting::builder::CharSet;
    /// # use ara_reporting::Report;
    /// # let report = Report::new();
    /// # let source = SourceMap::new(vec![
    /// #     Source::inline(SourceKind::Script, "function main(): void {}"),
    /// # ]);
    /// # let builder = ReportBuilder::new(&source);
    ///
    /// let builder = builder.with_charset(CharSet::Ascii);
    /// assert_eq!(builder.charset, CharSet::Ascii);
    ///
    /// let builder = builder.with_charset(CharSet::Unicode);
    /// assert_eq!(builder.charset, CharSet::Unicode);
    /// ```
    #[must_use]
    pub fn with_charset(mut self, charset: CharSet) -> Self {
        self.charset = charset;

        self
    }

    /// Set the display style
    ///
    /// Example:
    ///
    /// ```rust
    /// # use ara_source::source::Source;
    /// # use ara_source::source::SourceKind;
    /// # use ara_source::SourceMap;
    /// # use ara_reporting::builder::ReportBuilder;
    /// # use ara_reporting::builder::DisplayStyle;
    /// # use ara_reporting::Report;
    /// # let report = Report::new();
    /// # let source = SourceMap::new(vec![
    /// #     Source::inline(SourceKind::Script, "function main(): void {}"),
    /// # ]);
    /// # let builder = ReportBuilder::new(&source);
    ///
    /// let builder = builder.with_style(DisplayStyle::Default);
    /// assert_eq!(builder.style, DisplayStyle::Default);
    ///
    /// let builder = builder.with_style(DisplayStyle::Comfortable);
    /// assert_eq!(builder.style, DisplayStyle::Comfortable);
    ///
    /// let builder = builder.with_style(DisplayStyle::Compact);
    /// assert_eq!(builder.style, DisplayStyle::Compact);
    /// ```
    #[must_use]
    pub fn with_style(mut self, style: DisplayStyle) -> Self {
        self.style = style;

        self
    }

    /// Print the report to stdout.
    pub fn print(&self, reportable: &dyn Reportable) -> Result<(), Error> {
        let mut writer = StandardStream::stdout(match self.colors {
            ColorChoice::Always => match self.charset {
                CharSet::Ascii => TermColorChoice::AlwaysAnsi,
                CharSet::Unicode => TermColorChoice::Always,
            },
            ColorChoice::Auto => TermColorChoice::Auto,
            ColorChoice::Never => TermColorChoice::Never,
        });

        self.write(&mut writer, reportable)
    }

    /// Print the report to stderr.
    pub fn eprint(&self, reportable: &dyn Reportable) -> Result<(), Error> {
        let mut writer = StandardStream::stderr(match self.colors {
            ColorChoice::Always => match self.charset {
                CharSet::Ascii => TermColorChoice::AlwaysAnsi,
                CharSet::Unicode => TermColorChoice::Always,
            },
            ColorChoice::Auto => TermColorChoice::Auto,
            ColorChoice::Never => TermColorChoice::Never,
        });

        self.write(&mut writer, reportable)
    }

    /// Get the report as a string.
    pub fn as_string(&self, reportable: &dyn Reportable) -> Result<String, Error> {
        let buffer = BufferWriter::stderr(match self.colors {
            ColorChoice::Always => match self.charset {
                CharSet::Ascii => TermColorChoice::AlwaysAnsi,
                CharSet::Unicode => TermColorChoice::Always,
            },
            ColorChoice::Auto => TermColorChoice::Auto,
            ColorChoice::Never => TermColorChoice::Never,
        });

        let mut buffer = buffer.buffer();

        self.write(&mut buffer, reportable)?;

        Ok(String::from_utf8_lossy(buffer.as_slice()).to_string())
    }

    /// Write the report to the given writer.
    pub fn write<T: WriteColor>(&self, mut w: T, reportable: &dyn Reportable) -> Result<(), Error> {
        let mut styles = Styles::default();

        styles.secondary_label.set_bold(true);
        styles.line_number.set_fg(Some(Color::Ansi256(8)));
        styles.source_border.set_fg(Some(Color::Ansi256(8)));

        let config = Config {
            display_style: match self.style {
                DisplayStyle::Default => CodespanDisplayStyle::Rich,
                DisplayStyle::Comfortable => CodespanDisplayStyle::Medium,
                DisplayStyle::Compact => CodespanDisplayStyle::Short,
            },
            chars: match self.charset {
                CharSet::Ascii => Chars::ascii(),
                CharSet::Unicode => Chars::box_drawing(),
            },
            tab_width: 2,
            styles,
            start_context_lines: 1,
            end_context_lines: 1,
        };

        let mut files = SimpleFiles::new();
        let mut files_ids = FxHashMap::default();
        self.source_map.sources.iter().for_each(|source| {
            files_ids.insert(
                source.name().to_string(),
                files.add(source.name(), &source.content),
            );
        });

        for report in reportable.to_reports() {
            let diagnostics = self.diagnostics(report, &files_ids);

            for diagnostic in diagnostics {
                match emit(&mut w, &config, &files, &diagnostic) {
                    Ok(_) => (),
                    Err(err) => match err {
                        CodespanError::FileMissing => Err(Error::FileMissing)?,
                        CodespanError::IndexTooLarge { given, max } => {
                            Err(Error::IndexTooLarge { given, max })?
                        }
                        CodespanError::LineTooLarge { given, max } => {
                            Err(Error::LineTooLarge { given, max })?
                        }
                        CodespanError::ColumnTooLarge { given, max } => {
                            Err(Error::ColumnTooLarge { given, max })?
                        }
                        CodespanError::InvalidCharBoundary { given } => {
                            Err(Error::InvalidCharBoundary { given })?
                        }
                        CodespanError::Io(err) => Err(Error::Io(err))?,
                        other => Err(Error::CodespanError(other))?,
                    },
                }
            }
        }

        Ok(())
    }

    fn diagnostics(
        &self,
        report: &Report,
        files_ids: &FxHashMap<String, usize>,
    ) -> Vec<Diagnostic<usize>> {
        let mut diagnostics = Vec::new();

        for issue in &report.issues {
            let mut diagnostic = Diagnostic::new(issue.severity.into())
                .with_message(&issue.message)
                .with_notes(issue.notes.clone())
                .with_labels(
                    issue
                        .annotations
                        .iter()
                        .map(|annotation| {
                            let mut label = Label::new(
                                match annotation.r#type {
                                    AnnotationType::Primary => LabelStyle::Primary,
                                    AnnotationType::Secondary => LabelStyle::Secondary,
                                },
                                *files_ids.get(&annotation.origin).unwrap_or(&0),
                                annotation.from..annotation.to,
                            );

                            if let Some(message) = &annotation.message {
                                label = label.with_message(message);
                            }

                            label
                        })
                        .collect(),
                );

            if let Some(code) = &issue.code {
                diagnostic = diagnostic.with_code(code);
            }

            if let Some((source, from, to)) = &issue.source {
                diagnostic = diagnostic.with_labels(vec![Label::primary(
                    *files_ids.get(source).unwrap_or(&0),
                    *from..*to,
                )])
            }

            diagnostics.push(diagnostic);
        }

        if let Some(footer) = &report.footer {
            let mut notes = footer.notes.clone();

            if footer.summary {
                let mut entries = FxHashMap::default();
                report.issues.iter().for_each(|issue| {
                    *entries.entry(issue.severity).or_insert(0) += 1;
                });

                let mut entries = entries.iter().collect::<Vec<(&IssueSeverity, &usize)>>();
                entries.sort_by_key(|severity| *severity);

                let summary = entries
                    .iter()
                    .map(|(severity, count)| format!("{count} {severity}(s)"))
                    .collect::<Vec<String>>()
                    .join(", ");

                notes.push(format!("summary: {summary}"));
            }

            diagnostics.push(
                Diagnostic::new(report.severity().unwrap_or(IssueSeverity::Error).into())
                    .with_message(&footer.message)
                    .with_notes(notes),
            );
        }

        diagnostics
    }
}